1 //! Defines ECDSA-specific signer types.
3 use bitcoin::blockdata::transaction::Transaction;
5 use bitcoin::secp256k1::{PublicKey, Secp256k1, SecretKey};
6 use bitcoin::secp256k1::ecdsa::Signature;
7 use bitcoin::secp256k1;
9 use crate::util::ser::Writeable;
10 use crate::ln::PaymentPreimage;
11 use crate::ln::chan_utils::{HTLCOutputInCommitment, HolderCommitmentTransaction, CommitmentTransaction, ClosingTransaction};
12 use crate::ln::msgs::UnsignedChannelAnnouncement;
14 #[allow(unused_imports)]
15 use crate::prelude::*;
17 use crate::sign::{ChannelSigner, HTLCDescriptor};
19 /// A trait to sign Lightning channel transactions as described in
20 /// [BOLT 3](https://github.com/lightning/bolts/blob/master/03-transactions.md).
22 /// Signing services could be implemented on a hardware wallet and should implement signing
23 /// policies in order to be secure. Please refer to the [VLS Policy
24 /// Controls](https://gitlab.com/lightning-signer/validating-lightning-signer/-/blob/main/docs/policy-controls.md)
25 /// for an example of such policies.
26 pub trait EcdsaChannelSigner: ChannelSigner {
27 /// Create a signature for a counterparty's commitment transaction and associated HTLC transactions.
29 /// Note that if signing fails or is rejected, the channel will be force-closed.
31 /// Policy checks should be implemented in this function, including checking the amount
32 /// sent to us and checking the HTLCs.
34 /// The preimages of outbound and inbound HTLCs that were fulfilled since the last commitment
35 /// are provided. A validating signer should ensure that an outbound HTLC output is removed
36 /// only when the matching preimage is provided and after the corresponding inbound HTLC has
37 /// been removed for forwarded payments.
39 /// Note that all the relevant preimages will be provided, but there may also be additional
40 /// irrelevant or duplicate preimages.
42 // TODO: Document the things someone using this interface should enforce before signing.
43 fn sign_counterparty_commitment(&self, commitment_tx: &CommitmentTransaction,
44 inbound_htlc_preimages: Vec<PaymentPreimage>,
45 outbound_htlc_preimages: Vec<PaymentPreimage>, secp_ctx: &Secp256k1<secp256k1::All>,
46 ) -> Result<(Signature, Vec<Signature>), ()>;
47 /// Creates a signature for a holder's commitment transaction.
49 /// This will be called
50 /// - with a non-revoked `commitment_tx`.
51 /// - with the latest `commitment_tx` when we initiate a force-close.
53 /// This may be called multiple times for the same transaction.
55 /// An external signer implementation should check that the commitment has not been revoked.
57 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
58 /// signature and should be retried later. Once the signer is ready to provide a signature after
59 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
62 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
64 // TODO: Document the things someone using this interface should enforce before signing.
65 fn sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction,
66 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
67 /// Same as [`sign_holder_commitment`], but exists only for tests to get access to holder
68 /// commitment transactions which will be broadcasted later, after the channel has moved on to a
69 /// newer state. Thus, needs its own method as [`sign_holder_commitment`] may enforce that we
70 /// only ever get called once.
71 #[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
72 fn unsafe_sign_holder_commitment(&self, commitment_tx: &HolderCommitmentTransaction,
73 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
74 /// Create a signature for the given input in a transaction spending an HTLC transaction output
75 /// or a commitment transaction `to_local` output when our counterparty broadcasts an old state.
77 /// A justice transaction may claim multiple outputs at the same time if timelocks are
78 /// similar, but only a signature for the input at index `input` should be signed for here.
79 /// It may be called multiple times for same output(s) if a fee-bump is needed with regards
80 /// to an upcoming timelock expiration.
82 /// Amount is value of the output spent by this input, committed to in the BIP 143 signature.
84 /// `per_commitment_key` is revocation secret which was provided by our counterparty when they
85 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
86 /// not allow the spending of any funds by itself (you need our holder `revocation_secret` to do
89 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
90 /// signature and should be retried later. Once the signer is ready to provide a signature after
91 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
94 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
95 fn sign_justice_revoked_output(&self, justice_tx: &Transaction, input: usize, amount: u64,
96 per_commitment_key: &SecretKey, secp_ctx: &Secp256k1<secp256k1::All>
97 ) -> Result<Signature, ()>;
98 /// Create a signature for the given input in a transaction spending a commitment transaction
99 /// HTLC output when our counterparty broadcasts an old state.
101 /// A justice transaction may claim multiple outputs at the same time if timelocks are
102 /// similar, but only a signature for the input at index `input` should be signed for here.
103 /// It may be called multiple times for same output(s) if a fee-bump is needed with regards
104 /// to an upcoming timelock expiration.
106 /// `amount` is the value of the output spent by this input, committed to in the BIP 143
109 /// `per_commitment_key` is revocation secret which was provided by our counterparty when they
110 /// revoked the state which they eventually broadcast. It's not a _holder_ secret key and does
111 /// not allow the spending of any funds by itself (you need our holder revocation_secret to do
114 /// `htlc` holds HTLC elements (hash, timelock), thus changing the format of the witness script
115 /// (which is committed to in the BIP 143 signatures).
117 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
118 /// signature and should be retried later. Once the signer is ready to provide a signature after
119 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
122 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
123 fn sign_justice_revoked_htlc(&self, justice_tx: &Transaction, input: usize, amount: u64,
124 per_commitment_key: &SecretKey, htlc: &HTLCOutputInCommitment,
125 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
126 /// Computes the signature for a commitment transaction's HTLC output used as an input within
127 /// `htlc_tx`, which spends the commitment transaction at index `input`. The signature returned
128 /// must be be computed using [`EcdsaSighashType::All`].
130 /// Note that this may be called for HTLCs in the penultimate commitment transaction if a
131 /// [`ChannelMonitor`] [replica](https://github.com/lightningdevkit/rust-lightning/blob/main/GLOSSARY.md#monitor-replicas)
132 /// broadcasts it before receiving the update for the latest commitment transaction.
134 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
135 /// signature and should be retried later. Once the signer is ready to provide a signature after
136 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
139 /// [`EcdsaSighashType::All`]: bitcoin::sighash::EcdsaSighashType::All
140 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
141 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
142 fn sign_holder_htlc_transaction(&self, htlc_tx: &Transaction, input: usize,
143 htlc_descriptor: &HTLCDescriptor, secp_ctx: &Secp256k1<secp256k1::All>
144 ) -> Result<Signature, ()>;
145 /// Create a signature for a claiming transaction for a HTLC output on a counterparty's commitment
146 /// transaction, either offered or received.
148 /// Such a transaction may claim multiples offered outputs at same time if we know the
149 /// preimage for each when we create it, but only the input at index `input` should be
150 /// signed for here. It may be called multiple times for same output(s) if a fee-bump is
151 /// needed with regards to an upcoming timelock expiration.
153 /// `witness_script` is either an offered or received script as defined in BOLT3 for HTLC
156 /// `amount` is value of the output spent by this input, committed to in the BIP 143 signature.
158 /// `per_commitment_point` is the dynamic point corresponding to the channel state
159 /// detected onchain. It has been generated by our counterparty and is used to derive
160 /// channel state keys, which are then included in the witness script and committed to in the
161 /// BIP 143 signature.
163 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
164 /// signature and should be retried later. Once the signer is ready to provide a signature after
165 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
168 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
169 fn sign_counterparty_htlc_transaction(&self, htlc_tx: &Transaction, input: usize, amount: u64,
170 per_commitment_point: &PublicKey, htlc: &HTLCOutputInCommitment,
171 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
172 /// Create a signature for a (proposed) closing transaction.
174 /// Note that, due to rounding, there may be one "missing" satoshi, and either party may have
175 /// chosen to forgo their output as dust.
176 fn sign_closing_transaction(&self, closing_tx: &ClosingTransaction,
177 secp_ctx: &Secp256k1<secp256k1::All>) -> Result<Signature, ()>;
178 /// Computes the signature for a commitment transaction's anchor output used as an
179 /// input within `anchor_tx`, which spends the commitment transaction, at index `input`.
181 /// An `Err` can be returned to signal that the signer is unavailable/cannot produce a valid
182 /// signature and should be retried later. Once the signer is ready to provide a signature after
183 /// previously returning an `Err`, [`ChannelMonitor::signer_unblocked`] must be called on its
186 /// [`ChannelMonitor::signer_unblocked`]: crate::chain::channelmonitor::ChannelMonitor::signer_unblocked
187 fn sign_holder_anchor_input(
188 &self, anchor_tx: &Transaction, input: usize, secp_ctx: &Secp256k1<secp256k1::All>,
189 ) -> Result<Signature, ()>;
190 /// Signs a channel announcement message with our funding key proving it comes from one of the
191 /// channel participants.
193 /// Channel announcements also require a signature from each node's network key. Our node
194 /// signature is computed through [`NodeSigner::sign_gossip_message`].
196 /// Note that if this fails or is rejected, the channel will not be publicly announced and
197 /// our counterparty may (though likely will not) close the channel on us for violating the
200 /// [`NodeSigner::sign_gossip_message`]: crate::sign::NodeSigner::sign_gossip_message
201 fn sign_channel_announcement_with_funding_key(
202 &self, msg: &UnsignedChannelAnnouncement, secp_ctx: &Secp256k1<secp256k1::All>
203 ) -> Result<Signature, ()>;
206 /// A writeable signer.
208 /// There will always be two instances of a signer per channel, one occupied by the
209 /// [`ChannelManager`] and another by the channel's [`ChannelMonitor`].
211 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
212 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
213 pub trait WriteableEcdsaChannelSigner: EcdsaChannelSigner + Writeable {}